1. Field of the Invention
The invention is directed to an improved high-pressure pump for a fuel injection system of an internal combustion engine.
2. Description of the Prior Art
One high-pressure pump known from German Patent Disclosure DE 198 29 548 A1 has a drive shaft and at least one pump element with a pump piston driven in a reciprocating motion by the drive shaft having a shaft segment embodied eccentrically to its pivot axis, and a ring is rotatably supported on this portion. The pump piston is braced on the ring via a support element. The rotary motion of the drive shaft is converted into a reciprocating motion of the pump piston via the ring, which does not rotate jointly with the drive shaft. In the contact region between the ring and the support element, high forces occur because of the pressure generated by the pump piston. To further reduce fuel consumption and emissions in internal combustion engines, increasingly high pressures in fuel injection are needed and must be generated by the high-pressure pump. As a result, the load on the components of the high-pressure pump and the wear to the ring and the support element both increase. Moreover, for reducing emissions, new fuels are being developed that in particular contain little sulfur, but the lubricating properties of the fuel are worsened as a result. For this reason, under some circumstances it is no longer possible to assure that the high-pressure pump will have a sufficiently long service life.